
//  SELECT * FROM hg_users
// 查询所有
// SELECT username,age FROM hg_users
// 查询特定
// SELECT * FROM hg_users WHERE age = 18
// >18 <18    >=18   <=18
// SELECT * FROM hg_users WHERE age = 18
// 查询特定年龄
// SELECT * FROM hg_users WHERE age > 20 AND age < 30
// SELECT * FROM hg_users WHERE age > 30 or age < 20
// 范围查询
// SELECT * from hg_users ORDER BY age ASC
// 根据年龄升序排序
// SELECT * FROM hg_users LIMIT 0, 2
// SELECT * FROM hg_users LIMIT (page-1)*size, size
// 分页查询(从第一个开始查，查2个)

// 模糊查询查询包含有二哥的
// SELECT * FROM hg_users WHERE username like "%二哥%"
// 模糊查询查询二哥开头的
// SELECT * FROM hg_users WHERE username like "二哥%"
// 模糊查询查询二哥结尾的
// SELECT * FROM hg_users WHERE username like "%二哥"



// 增加
// INSERT INTO hg_users(username, PASSWORD, is_show, create_time) VALUES("好谷二哥", "123456", "1", "2022-05-31-20:20:20")

// INSERT INTO hg_users SET username = "好谷学堂", PASSWORD = "123456", is_show = "1", create_time = "2022-05-31 20:23:40"




// 更新
// UPDATE 表名 set 属性 = 值 WHERE 条件
// UPDATE hg_users set age = 18 WHERE id = 5



// 删除

// delete from hg_users where id=4










